| 摘要 |
PURPOSE: To protect a sound power supply against the effect of a failed power supply by monitoring the voltage of a switch means for feeding power from a plurality of power supplies to a load, detecting a failure in a power supply and disconnecting a failed power supply quickly. CONSTITUTION: First and second power supplies supply voltages Vp1 , Vp2 to FETs 25, 26 from which a voltage Vp0 is fed to a common load. LPFs 33, 47 and 30, 44 are connected, respectively, with the sources 34, 48 and the drains 31, 45 of the FETs 25, 26 and the voltages between the input and output of the FETs 25, 26 are monitored by comparators 28, 40. When the voltage Vp0 is lower than the voltages Vp1 , Vp2 , the comparators 28, 40 output a level H which energizes the gates 27, 42 of the FETs 25, 26 thus sustaining ON state of the FETs 25, 26. When the voltages Vp1 , Vp2 is lower than the voltage Vp0 , the comparators 28, 40 output a level L which turns the FETs 25, 26 off. Consequently, a failure is detected quickly and adverse effect on a sound power supply can be prevented. |
